Method of Manufacturing a Semiconductor Device

ABSTRACT

The objective of the invention is to provide a method of manufacturing a semiconductor device that allows individual molding of plural semiconductor chips carried on a surface of the substrate. It includes the following process steps: a process step in which plural semiconductor elements  102  are arranged on the surface of substrate  100 ; a process step in which the inner side of substrate  102  is fixed on lower die  130 ; a process step in which liquid resin  114  is supplied from nozzle  112  onto each of the semiconductor elements in order to cover at least a portion of each of semiconductor chips  102 ; a process step in which the upper die having plural cavities  144  formed in one surface is pressed onto the lower die, and liquid resin  114  is molded at a prescribed temperature by means of plural cavities  144 ; and a process step in which cavities  144  of upper die  140  are detached from the substrate, and plural molding resin portions are formed individually.

FIELD OF THE INVENTION

The present invention is concerned with the methods for sealing pluralsemiconductor chips mounted on one surface of a substrate, especially amolding method which can be adapted for the development of small, thinsemiconductor devices.

The popularity of cell phones, portable computers, and other smallelectronic equipment, has created ever-increasing demand for thedevelopment of small, thin semiconductor devices installed in them. Inorder to meet this demand, researchers have developed BGA and CSPpackages, which have been adopted in practical applications.

Patent Reference 1 discloses a type of BGA package. As shown in FIG. 13,plural copper pattern portions 4 are formed on the surface of insulatingfilm substrate 3 made of polyimide for electric connection betweensemiconductor chip 2 and solder bumps 7. One end of each said copperpattern portion 4 is connected via through-hole 3 a formed in insulatingfilm substrate 3 to solder bump 7. The other end of copper patternportion 4 is connected to one end of conductor wire 5 that extends fromelectrode pad 2 a of semiconductor chip 2. Solder resist 6 made of epoxyresin is coated on insulating substrate 3 containing said copper patternportions 4. Said semiconductor chip 2 is bonded on die attaching tape 8.It is then sealed in molding resin 9 molded using the transfer moldingmethod.

Also, Patent Reference 2 discloses a type of molding die that performsresin molding for workpieces to be molded having plural semiconductorchips mounted in a matrix shape on one surface of the substrate, and aresin molding method using said molding die. FIG. 14( b) is a diagramillustrating an example of the semiconductor package of the QFN (QuadFlat Non-leaded) type. In this case, semiconductor chips 52 are mountedin a matrix configuration on die pad portion 57 on one surface ofleadframe 56 as the workpiece to be molded. Each semiconductor chip 52and its surrounding lead portion 58 are wire bonded, and the electrodeportion of semiconductor chip 52 and one surface of lead portion 58serving as the terminal connecting portion are electrically connected toeach other by bonding wires 54. When resin substrate 51 and leadframe 56are carried on lower die 59, semiconductor chips 52 arranged in a matrixconfiguration are accommodated in cavity recess 60. Said resin substrate51 and leadframe 56 are clamped at the peripheral edge portion of thesubstrate by upper die 61 and lower die 59. The molding resin issupplied through lower runner gate 62 to fill cavity recess 60 so thatone surface is resin molded as a block. After resin molding, the molding(resin substrate 51 and leadframe 56) is diced into pieces, eachcontaining a semiconductor chip. The semiconductor devices aremanufactured in this way. C represents the dicer cutting lines.

-   [Patent Reference 1] Japanese Kokai Patent Application No.    2000-31327-   [Patent Reference 2] Japanese Kokai Patent Application No.    2003-234365

However, the aforementioned molding methods of the prior art have thefollowing problems. As shown in FIG. 14, when plural semiconductor chipsmounted on a surface of the substrate are molded as a block, cracksdevelop at the cut surfaces of the molding resin when it is cut alongthe dicer cutting lines C. Also, particles are generated in conjunctionwith cutting. In addition, when the plural semiconductor chips aremolded as a block, it is necessary to feed unnecessary resin betweenadjacent semiconductor chips, so that wasted resin results. This hampersefforts to make the outer dimensions of the molding resin smaller andthinner.

Also, the stacked IC package assembly form has become popular. A stackedIC package is supplied through a reflowing oven while it is assembled ona mother substrate, exposing it to a high temperature. As a result, thedifference in thermal expansion coefficients of the principal materialsused in the package cause mechanical warping. This warping prevents theterminals of the package (solder balls) from making contact with theterminals on the mother substrate, leading to contact defects.

Stacked IC packages usually make use of the transfer molding scheme. Inthis scheme, hot liquefied resin is poured into an injection port knownas a gate, and the gate is mechanically cut after partial curing of theresin in order to form an integral molding. Because the gate is cutmechanically, the outer dimensional accuracy and the appearance of thepackage may become defective. In addition, residual resin is createdafter resin sealing, and this leads to poor assembly when the IC packageis stacked.

The objective of the present invention is to solve the aforementionedproblems of the prior art by providing a method of manufacturing asemiconductor device that allows individual molding of pluralsemiconductor chips mounted on one surface of a substrate.

In addition, the objective of the present invention is to provide amethod of manufacturing a semiconductor device that can make the moldedresin over the plural semiconductor chips mounted on one surface of thesubstrate be small and thin.

In addition, the objective of the present invention is to provide a typeof semiconductor device and its manufacturing method that allows anothersurface assembly type of semiconductor device to be stacked on thesurface where the molding resin is formed.

SUMMARY OF THE INVENTION

The present invention provides a method of manufacturing a semiconductordevice characterized by the following facts: in a method ofmanufacturing a semiconductor device wherein semiconductor elements aremounted on a substrate sealed with a resin, plural semiconductorelements are arranged on the first principal surface of the substrate;the second principal surface opposite to the first principal surface ofthe substrate is fixed on a supporting part (lower die); a liquid resinis supplied to each of the semiconductor elements to cover at least aportion of each semiconductor element; a mold part (upper die) havingplural recesses (cavities) formed in one surface is pressed onto thesupporting member, and the liquid resin for each semiconductor elementis molded within each said recess at a prescribed temperature; and therecesses of the mold part are released from the substrate.

The process step in which the liquid resin is supplied includes aprocess step in which a nozzle for supplying liquid resin is driven toscan the first principal surface of the substrate. It is preferred thatthe quantity supplied be in the range of ±3% with respect to the volumeof the recess of the mold part. Also, it is preferred that the liquidresin be in liquid form at room temperature, and it have a viscosity inthe range of 30-150 Pa s.

The liquid resin is molded at about 150° C. In this case, a flexiblefilm may be adhered on the plural recesses of the mold part. Theflexible film acts as a mold release material for the molding resin. Itis preferred that the softening temperature of the film be near thetemperature at which the liquid resin is molded. In addition, thesurface of the film that is to contact the plural recesses is rough, andthe film is preferably at least 50 μm thick so that it can cover thesteps formed on the substrate. For example, the film is made of athermoplastic fluorine-containing resin (ETFE).

For the manufacturing method, it is preferred that there also be aprocess step in which the atmosphere around the liquid resin isevacuated before molding the liquid resin by means of the recesses ofthe mold part. Because the atmosphere of the semiconductor element isevacuated, it is possible to inhibit gas bubbles and voids in themolding resin. The degree of absolute vacuum is 5 kPa or better.

In addition, the mold part contains plural pressing members withrecesses formed in them, and the various pressing members areindependently supported in an elastic way. The liquid resin supplied toeach semiconductor element is pressed individually.

The manufacturing method also includes a process step in which thesubstrate is cut to correspond to the area of the molded semiconductorelements, a process step in which connecting terminals are attached onthe second principal surface, and a process step in which anothersemiconductor device is stacked onto the first principal surface of thesubstrate.

The semiconductor device of the present invention has anothersemiconductor device stacked onto the semiconductor device manufacturedin the aforementioned process step. In this case, a wiring pattern isformed on the first principal surface of the substrate, and the pluralconnecting terminals formed on the inner surface of anothersemiconductor device are electrically connected to the aforementionedwiring pattern. For example, the connecting terminals of said anothersemiconductor device are for BGA or CSP packages, and these terminalsare arranged on the outer periphery of the molding resin. As a result,the molding resin is sandwiched between the substrate of saidsemiconductor device and said another semiconductor device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: FIG. 1( a) is a plan view of a substrate with pluralsemiconductor chips mounted on it. FIG. 1( b) is a cross section takenacross line A-A.

FIG. 2 is a diagram illustrating a process in the molding method in anembodiment of the present invention.

FIG. 3 is a diagram illustrating a process in the molding method in anembodiment of the present invention.

FIG. 4 is a diagram illustrating a process in the molding method in anembodiment of the present invention.

FIG. 5 is a diagram illustrating a process in the molding method in anembodiment of the present invention.

FIG. 6 is a diagram illustrating a process in the molding method in anembodiment of the present invention.

FIGS. 7( a) and 7(b) show a process in the molding method of anembodiment of the present invention. FIG. 7( a) is a plan view of asubstrate with molding resin formed on it. FIG. 7( b) is a cross sectiontaken across A1-A1.

FIGS. 8( a) and 8(b) show the upper die pertaining to Embodiment 2 ofthe present invention. FIG. 8( a) is a plan view of the upper die asseen from the inner side, and FIG. 8( b) is a cross section of thechamfer portion.

FIG. 9 is a diagram illustrating the outer shape of the molding resin inEmbodiment 2.

FIG. 10 is a schematic cross section of the stacked structure of thesemiconductor device.

FIG. 11 is a diagram illustrating warping of the semiconductor device.

FIG. 12( a) is a table listing the resin characteristics of the liquidresin and FIG. 12( b) is a table listing the dimensions of the mainportion of the semiconductor device.

FIG. 13( a) is an oblique view of a conventional BGA and FIG. 13( b)depicts a portion of the cross section of a conventional BGA package.

FIG. 14( a) and FIG. 14( b) depicts the method of molding a matrixsubstrate in the prior art.

REFERENCE NUMERALS AND SYMBOLS AS SHOWN IN THE DRAWINGS

In the figures, 100 represents a substrate, 102, 210, 304, 306 representsemiconductor chips, 104, 212 represent bonding wires, 110 represents acontainer, 112 represents a nozzle, 114 represents a liquid resin, 130represents a lower die, 140 represents an upper die, 142 represents arelease film, 144 represents a cavity, 146 represents a pressure member,150 represents an air suction hole, 152 represents a leg portion, 160,184, 206, 410 represent molding resin, 170, 186 represent chamfers, 180represents an air pocket, 182 represents a land, 188 represents aprotrusion, 200 represents a first semiconductor device, 202 representsa multilayer wiring substrate, 204 represent solder balls, 208represents a die attachment, 300 represents a second semiconductordevice.

DESCRIPTION OF THE EMBODIMENTS

According to the present invention, it is preferred that resin sealingof the plural semiconductor elements formed as a block on one surface ofthe substrate be performed individually. As a result, it is possible toprovide a small, thin semiconductor device. In addition, because pluralsemiconductor elements are individually sealed by resin, it is possibleto prevent waste of the molding resin. At the same time, it is possibleto obtain individual semiconductor devices without dicing the moldingresin, so that the shear stress or the like that results when themolding resin is cut is not directly applied. Consequently, no cracksare generated in the molding resin, the dimensional accuracy of themolding resin becomes consistent, and a high-quality appearance can beguaranteed.

PREFERRED EMBODIMENT OF THE INVENTION

In the following, preferred embodiments of the present invention will beexplained with reference to figures.

FIG. 1( a) is a plan view illustrating a substrate with pluralsemiconductor chips mounted on it, and FIG. 1( b) is a cross sectiontaken across A-A. In the first embodiment, plural semiconductor chipsare set in matrix configuration on one surface of substrate 100. Thereis no special limitation on the constitution of said substrate 100. Itis possible to adopt multilayer wiring substrates and film substrates.For example, a glass epoxy resin, polyimide resin, or other insulatingsubstrate can be used. Said semiconductor chips 102 are attached via dieattachment or the like at the prescribed positions of substrate 100. Theelectrodes of semiconductor chips 102 are connected to the copperpattern formed on the surface of substrate 100 by means of bonding wires104.

In the following, the method will be explained for individually moldingsaid semiconductor chips 102 mounted on the substrate shown in FIG. 1 asa block. As shown in FIG. 2, container 110 filled with liquid resin isdriven to scan substrate 100 in longitudinal direction P, and liquidresin 114 is fed from tip nozzle 112 onto substrate 100. In this case,liquid resin 114 is supplied intermittently from tip nozzle 112 to coverthe surface of individual semiconductor chips 102. As a result, liquidresin 114 is not supplied to regions 116 between semiconductor chips102, so that the substrate there is left exposed. The quantity suppliedof liquid resin 114 depends on the dimensional accuracy of the moldingresin. Consequently, it should be controlled with high precision. It ispreferred that liquid resin 114 be supplied within ±3% of the volume ofcavity 144 of upper die 140, to be explained later.

With regard to the characteristics of liquid resin 114, it is in liquidform at room temperature, and its viscosity is about 30-150 Pa s, orpreferably 45 Pa s. A consistent viscosity for liquid resin 114 makes itpossible to effectively cover the entirety of semiconductor chip 102with liquid resin 114 supplied from the nozzle. For example, one maymake use of an epoxy resin as liquid resin 114, and it can havequick-curing properties.

Then, as shown in FIG. 3, substrate 100 is placed on lower die 130. Itis preferred that pins or the like for positioning substrate 100 beprovided on lower die 130. In this embodiment, the substrate with liquidresin 114 having been fed onto semiconductor chip 102 is placed on lowerdie 130. However, the present invention is not limited to this scheme.For example, a scheme can also adopted in which liquid resin 114 is fedonto semiconductor chip 102 while semiconductor chip 102 is in place onlower die 130.

Release film 142 is then prepared on the pressure surface side of upperdie 140. Plural recesses, that is, cavities 144, are formed in thepressure surface side of upper die 140. These cavities 144 are arrangedcorresponding to the positions of semiconductor chips 102 on thesubstrate fixed on the lower die. Pressing member 146 is provided ineach cavity 144, and pressing member 146 is elastically supported byspring 148. Said cavity 144 is a rectangular recess surrounded by thepressure surface of pressing member 146 and the side surfaces of legportions 152, and it defines the outer shape of the molded moldingresin. For example, the dimensions of cavity 144 surrounded by the sidesurfaces of leg portions 152 and by pressing member 146 are 10.9 mm inwidth, 10.9 mm in length, and 0.27 mm in height. Also, for example, thedimensions of semiconductor chip 102 are 8.8 mm in width, 8.6 mm inlength, and 0.1 mm in height.

In addition, air suction hole 150 connected to each cavity 144 is formedin upper die 140. By sucking air through said air suction hole 150,release film 142 is sucked in and adhered along the pressure surface ofcavity 144 of upper die 140.

Said release film 142 is supplied from reel 154, and it is taken up byreel 156 (see FIG. 3). Said release film 142 is flexible and heatresistant, and it preferably has the property that it softens at atemperature lower than the temperature of heated upper die 140. In thisembodiment, because upper die 140 is heated to about 150° C., thesoftening temperature of release film 142 is selected to be near 150° C.For example, a flexible film of a thermoplastic fluorine-containingresin (ETFE) can be used.

Also, it is preferred that release film 142 be at least 50 μm thick. Aswill be explained later, when liquid resin 114 is molded, release film142 is pressed against substrate 100 by leg portion 152. In this case,liquid resin 114 does not squeeze out from the contact interface betweenrelease film 142 and substrate 100. A copper pattern and solder resistare formed on the surface of substrate 100, creating a step of about 20μm from the surface of the substrate. The thickness of release film 142is selected to be 50 μm or greater or sufficient to cover the step. Morespecifically, one surface of release film 142 is processed to roughenit. For example, the roughness can be Rz: 15 μm. The surface that hasbeen processed to roughen it is in contact with upper die 140. As aresult, after molding of the liquid resin, release film 142 can bereleased easily from upper die 140 and wound up on reel 156.

Then, as shown in FIG. 4, upper die 140 is positioned near lower die130. When they have approached within a prescribed distance of eachother, upper die 140 comes into contact with the O-ring (not shown inthe figure) of lower die 130, the air in cavity 144 is evacuated, and avacuum is established within cavity 142. It is preferred that the degreeof absolute vacuum be 5 kPa or better. Also, said upper die 140 andlower die 130 are heated to about 150° C.

Then, as shown in FIG. 5, upper die 140 is lowered so that leg portions152 come into contact with substrate 100 with a prescribed contactpressure. As a result, a sealed space is formed over the regionincluding the various semiconductor chips on the substrate. Saidpressing member 146 in each cavity 144 makes an elastic pressure moldingfor liquid resin 114 via release film 142. This state is maintained forabout 100 sec. During this period, because leg portions 152 are incontact with substrate 100 at a prescribed contact pressure, no liquidresin 114 is squeezed out of cavity 144. In this way, because liquidresin 114 is pressed and molded at a constant temperature, the moldingresin is molded to a shape that reflects the shape of cavity 144.

Then, as shown in FIG. 6, upper die 140 is released from lower die 130,and release film 142 is released from the pressure surface of upper die140 and is wound up on reel 146. At the same time, molding resin 160 onthe substrate is released from release film 142. Molding resin portions160 formed in the same quantity as that of the semiconductor chips areformed on substrate 100, and this molding resin 160 seals off the regioncontaining semiconductor chip 102 and bonding wire 104.

Then, as shown in FIG. 7, substrate 100 is removed from lower die 130.Molding resin 160 to seal semiconductor chip 102 is formed on substrate100 that is very thin and occupies a very small area.

The subsequent process steps include a process step in which solderballs are connected to the inner surface of substrate 100 as connectingterminals, and a process step in which the substrate is diced. In thedicing process step, the substrate is cut along dicing lines Cpositioned between molding resin portions 160, 160. That is, moldingresin 160 is not cut in the dicing process step. Consequently, the outershape of molding resin 160 can keep the shape of the cavity as is. As aresult, it is possible to eliminate the generation of particles, cracksin the molding resin, and other problems.

In the following, a second embodiment will be explained. In the firstembodiment, the internal shape of cavity 144 (recess) of upper die 140is rectangular. In Embodiment 2, air pockets are formed at the chamfersat the corners of each cavity 144.

FIG. 8( a) is a schematic plan view of one pressing portion of upper die140 as viewed from the inner side. FIG. 8( b) is a cross section of aportion of the chamfer region. Chamfer 170 is formed at each corner ofcavity 144 of upper die 140. In addition, chamfer 170 extends in adiagonal line and is connected to an air pocket 180, a prescribed closedinternal space. Said air pocket 180 at each corner is in a vacuum stateand can absorb voids when the liquid resin is molded. That is, when theliquid resin is used in press molding with the interior of cavity 144 inthe evacuated state, voids from gas bubbles, etc., in the liquid resinare pressed toward air pocket 180, so that voids are unlikely to remainin the molding resin after the molding operation.

FIG. 9 is a plan view illustrating the state in which the semiconductorelement has been molded using the upper die in Embodiment 2. To simplifythe explanation, only a single region of the substrate is shown here. Onthe upper surface of substrate 100, plural lands 182 are formedconnected to a copper pattern. Said lands 182 are regions connected tothe solder balls on the inner surface of the substrate via thethrough-holes formed in substrate 100. The various semiconductorelements on substrate 100 are sealed by molding resin 184. Said moldingresin 184 has chamfers 186 formed at the corners matching cavity 144 inupper die 140. In addition, fine protrusions 188 corresponding to airpockets 180 are formed on chamfers 186 of molding resin 184.

In this embodiment, it is possible to eliminate the generation of voidsin molding resin 184 by providing air pockets 180. Consequently, it ispossible to increase the package yield. The size of air pocket 180should be appropriate to provide a prescribed volume for absorbing thevoids. The acceptable size should permit said fine protrusion 188 to beseparated by a prescribed distance D from land 182.

In the following, a third embodiment of the present invention will beexplained. FIG. 10 is a cross section illustrating the POP (Package OnPackage) structure in which a second semiconductor device is stacked ona first semiconductor device formed using the molding method inEmbodiment 1.

Said first semiconductor device 200 has a BGA package composed ofmultilayer wiring substrate 202 0.3 mm thick, plural solder balls 2040.23 mm high formed on the inner surface of multilayer wiring substrate202, and molding resin 206 formed on the upper surface of multilayerwiring substrate 202. On the upper surface of multilayer wiringsubstrate 202, semiconductor chips 210 are attached via die attachment208, and the electrodes of semiconductor chips 210 are connected tocopper pattern 214 on the substrate by means of bonding wires 212. Theregion containing semiconductor chip 210 and bonding wires 212 is sealedwith molding resin 206. The loop height of bonding wires 212 from thechip surface is about 0.05 mm. The distance from bonding wires 212 tothe surface of molding resin 206 is about 0.095 mm, and the height ofthe entire package of the first semiconductor device is 0.8 mm.

Second semiconductor device 300 is stacked on said first semiconductordevice 200. For example, said second semiconductor device 300 hassemiconductor chips 304, 306 stacked on the upper surface of substrate302 and has said semiconductor chips 304, 306 sealed by molding resin308. Said molding resin 308 may be of the transfer molding type. Tworows of solder balls 310 are formed in 4 directions on the inner surfaceof substrate 302.

When second semiconductor device 300 is stacked on first semiconductordevice 200, solder balls 310 are arranged surrounding molding resin 206.Solder balls 310 of the second semiconductor device are connected toelectrodes 216 formed on the upper surface of substrate 202 of firstsemiconductor device 200. The height of molding resin 206 from thesurface of substrate 202 is about 270 μm, and the height of solder balls310 from substrate 302 is a little larger. As a result, a small gap isformed between the inner surface of substrate 302 and molding resin 206.

In this way, when the manufacturing method of Embodiment 1 is adopted,by stacking the second semiconductor device on first semiconductordevice 200 with very thin and small molding resin 206, it is possible toobtain a thin POP structure. It is similarly possible to obtain a thinPOP structure using the manufacturing method of Embodiment 2.

In the following, a fourth of the present invention will be explained.When semiconductor device 200 manufactured using the method inEmbodiment 1 (see FIG. 10) is assembled on a substrate, it is exposed toa high temperature when it is passed through a reflowing oven, so thatthe substrate warps. FIG. 11 illustrates schematically the warping ofthe semiconductor device. As shown in FIG. 11( a), substrate 400 andmolding resin 410 undergo positive warping to form a concave shape. Asshown in FIG. 11( b), they undergo negative warping to form a convexshape. Assuming the distances from the bottom surface of substrate 400to the top surface of molding resin 410 are h1 and h2, if the magnitudesof h1, h2 exceed 150 μm, defective bonding between the solder balls andthe substrate is apt to occur.

In this embodiment, in order to reduce warping h1, h2 of the substrate,a liquid resin is selected with the characteristics shown in FIG. 12(a). CTE1 is the linear expansion coefficient in the temperature regionbelow the glass transition temperature, and CTE2 represents the linearexpansion coefficient in the temperature region above the glasstransition temperature. YM1 represents the longitudinal modulus (Young'smodulus) in the temperature region below the glass transitiontemperature. YM2 represents the longitudinal modulus (Young's modulus)in the temperature region above the glass transition temperature. FIG.12( a) shows two conditions A, B. It is preferred that a liquid resincorresponding to condition B be used. Also, the constitution ofsemiconductor device 200 is shown in FIG. 12( b). The semiconductor chipis a silicon chip 8.8 mm wide, 8.6 mm long, 0.1 mm high. Also, themultilayer wiring substrate is made of BT with a linear expansioncoefficient of about 17 ppm in the temperature range of 30-200° C. Thedimensions are 1.4 mm wide, 1.4 mm long and 0.3 mm high.

In this constitution, the magnitudes of semiconductor device warping atroom temperature (for example, 25° C.) h1 and h2 are 80 μm or less, andthe warping magnitudes h1, h2 of the semiconductor device at hightemperature (for example, 260° C.) are 110 μm or less. As a result, goodsolder contact can be realized during substrate assembly.

Preferred embodiments of the present invention have been explained indetail above. However, the present invention is not limited to theseembodiments. Various modifications and changes can be made as long asthey remain within the scope of the present invention described in theclaims.

In the aforementioned embodiments, the method of manufacturing BGA orCSP type semiconductor devices has been described. However, other typesof semiconductor devices may also be adopted. There is no speciallimitation on the constitution of the package, and it is only requiredthat the semiconductor chips carried on one surface of the substrate besealed by resin. In addition, with regard to the method of assemblingthe semiconductor chips on the substrate, in addition to the connectionmethod using wire bonding, connection can also be performed by means ofthe face-down scheme. In addition, in the aforementioned embodiments thecavities formed in the upper die are rectangular. However, the cavitymay also have a sloping side surface so that the side surface of theresin molding is inclined.

The molding method of the semiconductor chip pertaining to the presentinvention can be used to substitute for the conventional transfermolding method and bonding method. By using the molding method of thepresent invention, an ultra-small and ultra-thin semiconductor devicewith high dimensional accuracy can be provided. In particular, it ispossible to realize an ultra-thin semiconductor device of the surfaceassembly type.

1. A semiconductor device comprising a substrate with wiring pattern ona first surface; a first semiconductor element disposed on the firstsurface; mold resin sealing the first semiconductor element and aportion of the wiring pattern; a second semiconductor element withconnecting terminals electrically connected to the wiring pattern; and aspace between the mold resin and second semiconductor element.
 2. Thesemiconductor device described in any of claim 1 in which the mold resinhas a glass transition temperature in the range of 100-160° C., acoefficient of thermal expansion in the temperature region below theglass transition temperature in the range of 20-30 ppm, a coefficient ofthermal expansion in the temperature region above the glass transitiontemperature in the range of 80-120 ppm, a longitudinal modulus in thetemperature region below the glass transition temperature in the rangeof 1-20 GPa, and a longitudinal modulus in the temperature region abovethe glass transition temperature in the range of 0.1-1.0 GPa.
 3. Thesemiconductor device described in any of claim 1 in which the mold resinhas a glass transition temperature in the range of 130-160° C., acoefficient of thermal expansion in the temperature region below theglass transition temperature in the range of 24-25 ppm, a coefficient ofthermal expansion in the temperature region above the glass transitiontemperature in the range of 90-100 ppm, a longitudinal modulus in thetemperature region below the glass transition temperature in the rangeof 9-11 GPa, and a longitudinal modulus in the temperature region abovethe glass transition temperature in the range of 0.2-0.5 GPa.